“In just over a year the proportion of ­people who say they will have to work past pension age has nearly doubled as it dawns on them their pensions are not going to give them enough income for a decent lifestyle.

“Working longer has become a necessity and it will probably be essential for the majority of people whose pensions are falling short of their expectations.”

The latest research, by Canada Life Group Insurance, found that 66 per cent of those surveyed said they would have to work past the age of 65.

Many Britons have failed to plan adequately for their retirement [GETTY]

The concept of retiring at 65 and no longer earning a wage is fast ­becoming antiquated

Paul Avis, Canada Life spokesman

Canada Life spokesman Paul Avis said: “The concept of retiring at 65 and no longer earning a wage is fast ­becoming antiquated as more and more employees accept they will be working long beyond the traditional retirement age.

“Increased life expectancies and recent economic difficulties have boosted the proportion who feel they will be forced into working longer than they want to in order to afford the rising cost of living.”

The survey of employees found that the soaring cost of living was the main reason they would have to supplement their pension with a wage. Just 28 per cent said they would continue working because they enjoyed their job.

Today almost one person in 10 over the age of 65 is still working – an increase of 10 per cent in a year. Experts have long warned that the UK faces a “time bomb” as so many Britons have failed to adequately plan for their retirement.

The closure of almost all “gold-plated” final salary pension schemes in the ­private sector has been one of the main causes.

Personal finance expert Yvonne Goodwin said those retiring mortgage-free today and wanting a “reasonable” lifestyle, including two holidays-a-year, need at least £25,000-a-year.

Mrs Goodwin said: “If you don’t plan, it will almost certainly mean working until you drop. It’s all a balance between the here and now and later life.

“But it’s not surprising so many have ignored it. If you stop to think how much you’ll need, it will make you sick with worry.

“We are already in a pensions time bomb because so many people have chosen to bury their heads in the sand. The situation is unsustainable.”

One reason people are working for longer is to keep benefits associated with employment, including private medical insurance, disability benefits and life assurance cover.

Canada Life’s Mr Avis said: “Employees considering working beyond the ­traditional retirement age should acknowledge the importance of appropriate workplace benefits, particularly as an older workforce will inevitably ­suffer from more health issues.

“Group benefits, such as income protection and critical illness cover, will ensure incomes are protected in the event of an accident or serious illness, preventing people from having to push back their retirement even further due to unexpected gaps in income.”